The Commens Dictionary
Quote from ‘The Basis of Pragmaticism’
…an equiparance; that is, the relation of B to A is essentially the same as that of A to B, so far as the duality of the pair is concerned. But no equiparance whatever, with the exception of the very few that are necessary, such as identity, coexistence, etc., is a logically simple relation.
‘Equiparance’ (pub. 14.08.17-09:22). Quote in M. Bergman & S. Paavola (Eds.), The Commens Dictionary: Peirce's Terms in His Own Words. New Edition. Retrieved from http://www.commens.org/dictionary/entry/quote-basis-pragmaticism-31.